(A) Flush all piping systems with water to remove any debris prior to testing. Water will be provided by the town.
(B) Gravity sewers.
(1) General. After backfill has been placed, the engineer will visually inspect all gravity flow lines to check alignment and grade. All obstructions shall be removed. Any sewer in which the direct light of a lamp cannot be viewed in either direction between adjacent manholes shall be considered unsatisfactory and shall be repaired by the contractor without additional compensation.
(2) Tests. All sewer system piping for gravity flow shall be subjected to .an air test rather than an infiltration or exhilaration tests. However, infiltration and exhilaration test methods have been included if requested by the engineer during construction. When leakage occurs in excess of the specified limits, defective pipe or joints shall be located and repaired. The contractor, at his or her own expense, shall remove and reconstruct, along with retesting, as much of the original work as necessary to obtain a sewer test within the allowable leakage limits.
(a) Air test. The sewer line to be tested shall be tested in increments between manholes. The line shall be sealed at each end. The seal at one end shall have an orifice through which to pass air into the pipe. An air supply shall be connected to the orifice at one end of the line. The air supply line shall contain an on/off gas valve and a pressure gauge having a range of from 0 to 5 psi. The gauge shall have minimum divisions of 0.10 psi and shall have an accuracy of plus or minus 0.04 psi.
(b) The pipeline under test shall be pressurized to 4 pig. The line shall be allowed to stabilize between 4 pig and 3.5 pig for a period of no less than five minutes. If necessary, air shall be added to the line to maintain the pressure above 3.5 pig. After the stabilization period, the gas valve shall be closed. When the line pressure drops to 3.5 pig, commence timing with a stop watch. The stop watch shall be allowed to run until such time as the line pressure drops to 2.5 .pig. Then the watch shall be stopped and the time lapse compared with the allowable time lapse shown.
Pipe Diameter in Inches | Minutes |
Pipe Diameter in Inches | Minutes |
4 | 2.0 |
6 | 3.0 |
8 | 4.0 |
10 | 5.0 |
12 | 5.5 |
15 | 7.5 |
18 | 8.5 |
21 | 10.0 |
24 | 11.5 |
(c) If the time lapse is greater than that specified, the section undergoing tests shall have passed. If the time is less than that specified, the line has not passed the test and the contractor shall be required to make all repairs and retests. If the pipeline to be tested is beneath the ground water level, the test pressure shall be increased .433 psi for each foot the ground water level is above the crown of the pipe.
(d) Furnish all equipment and personnel required to make all tests including pipe stoppers, air compressor, air storage tank, pressure regulating valves, pressure gauges, stopwatch, and the like. Take precautions necessary, including blocking of stoppers or plugs, to protect the safety of property and personnel.
(e) Infiltration tests. When the groundwater level is four feet above the top of the sewer, the infiltration test will consist of sealing off a length of sewer and measuring the depth of flow over a measuring weir, or by pumping the infiltrated water into containers for measurement. Tests shall be conducted for a minimum of four hours. Infiltration leakage shall not exceed 200 gallons per 24hours per inch diameter, per mile of sewer.
(f) Exhilaration tests. When the groundwater level is below a point four feet above the top of the pipe, the exfiltration test shall consist of isolating the particular section and filing the water to a point four feet above the ground water level in the upper manhole and allowing it to stand not less than four hours. The section shall then be refilled with water up to the original point and after two hours the drop in water surface shall be measured. The computed leakage shall not exceed 200 gallons per inch diameter, per 24 hours, per mile of sewer.
(3) Deflection tests shall be performed on all flexible pipe after the final backfill has been in place at least 30 days. No pipe shall exceed a vertical deflection of 5%. The following are considered nonflexible pipes:
(a) Vitrified clay pipe;
(b) Concrete pipe;
(c) Ductile iron pipe;
(d) Cast iron pipe;
(e) Asbestos cement pipe.
(C) Force mains.
(1) General. All sewage force mains shall pass a hydrostatic pressure test as specified. All buried piping with slip-type or mechanical joints shall pass a leakage test. No leakage is allowed in exposed piping or buried piping with flanged, threaded, welded or mechanical joints.
(2) Tests for exposed piping shall be made before covering and insulation is placed and prior to concealment within the building construction.
(3) The pressure and leakage tests for buried piping shall be made after all jointing operations and backfilling are completed, and concrete reaction blocks and restraints have cured at least 14 days. Piping tested before backfill is in place shall be retested after compacted backfill is placed.
(4) Sections of piping between valves, and other short sections of line may be isolated for testing. If shorter sections are tested, test plugs or bulkheads required at the ends of the test section shall be furnished and installed by the contractor, together with all anchors, braces, and other devices required to withstand the hydrostatic pressure without imposing any thrust on the pipeline. The contractor shall be solely responsible for any damage which may result from the failure of test plugs or supports.
(5) Hydrostatic tests. Piping systems shall be slowly filed with water and all air expelled from the pipe. Care shall be taken that all air valves are installed and open in the section being filled, and that the rate of filling does not exceed the venting capacity of the air valves. After the section of line to be tested has been filled with water, the specified test pressure shall be applied and maintained for a minimum period of two hours and for such additional period necessary for the engineer to complete the inspection of the line under test. If defects are noted, repairs shall be made and the test repeated until all parts of the line withstand the test pressure. Hydrostatic test pressures shall be 150% of design pressure, but not less than 150 psi. Test duration shall be two hours.
(6) Leakage test. After the specified hydrostatic test has been completed, the line shall be subjected to leakage test under a hydrostatic pressure the same as the pressure specified for the hydrostatic test. The pressure shall be maintained within a maximum variation of 5% during the entire leakage test. Leakage measurements shall not be started until a constant test pressure has been established. The line leakage shall be measured by means of water meter installed on the supply side of the pressure pump, or method as approved by the engineer.
(a) The tested section will not be accepted if it has a leakage rate in excess of that rate determined by the formula:
L = 0.000135 ND(P) in which; L =Maximum permissible leakage rate in gallons per hour throughout the entire length of line being tested. N =Number of gasketed joints (two for each flexible coupling joint) in the line under test. D =Nominal internal diameter (in inches) of the pipe. P = The actual pressure in psig on all joints in the tested portion of the line. This actual pressure shall be determined by finding the difference between the average elevation of all tested pipe joints and the elevation of the pressure gauge and adding the difference in elevation head to the required pressure. |
(b) Where the leakage rate exceeds the permissible maximum, the contractor shall locate and repair leaking joints to the extent required to reduce the total leakage to the required amount.
(c) All leaks discovered within one year from the date of final acceptance of the work by the owner shall be located, repaired and retested by the contractor, regardless of the total line leakage rate.
(Ord. 2002-5-1, passed 5-14-02; Am. Ord. 2013-3-1, passed 3-28-13)